#NEWS : NASA's Spitzer reveals first carbon-rich planet

LOS ANGELES, Dec. 8 (Xinhua) -- NASA's Spitzer Space Telescope has revealed a huge and searing-hot planet loaded with an unusual amount of carbon, the Jet Propulsion Laboratory (JPL) said on Wednesday.

Orbiting another star, the planet, a gas giant named WASP-12b, is the first carbon-rich world ever observed, the JPL said.

The discovery was made using NASA's Spitzer Space Telescope, along with previously published ground-based observations, according to the JPL in Pasadena, Los Angeles.

It's possible that WASP-12b might harbor graphite, diamond, or even a more exotic form of carbon in its interior, beneath its gaseous layers, the JPL said.

Astronomers don't currently have the technology to observe the cores of exoplanets, or planets orbiting stars beyond our sun, but their theories hint at these intriguing possibilities, said the JPL.

The research also supports theories that carbon-rich rocky planets much less massive than WASP-12b could exist around other stars, the JPL said.

Our Earth has rocks like quartz and feldspar, which are made of silicon and oxygen plus other elements. A carbon-rich rocky planet could be a very different place, the JPL explained.

"A carbon-dominated terrestrial world could have lots of pure carbon rocks, like diamond or graphite, as well as carbon compounds like tar," said Joseph Harrington of the University of Central Florida, in Orlando, who is the principal investigator of the research.

Carbon is a common component of planetary systems and a key ingredient of life on Earth. Astronomers often measure carbon-to- oxygen ratios to get an idea of a star's chemistry. Our sun has a carbon-to-oxygen ratio of about one to two, which means it has about half as much carbon as oxygen.

None of the planets in our solar system is known to have more carbon than oxygen, or a ratio of one or greater.

However, this ratio is unknown for Jupiter, Saturn, Uranus, and Neptune. Unlike WASP-12b, these planets harbor water -- the main oxygen carrier -- deep inside their atmospheres, making it hard to detect, according to the JPL.

WASP-12b is the first planet ever to have its carbon-to-oxygen ratio measured at greater than one (the actual ratio is most likely between one and two). This means the planet has excess carbon, some of which is in the form of atmospheric methane, the JPL said.

"This planet reveals the astounding diversity of worlds out there," said Nikku Madhusudhan of the Massachusetts Institute of Technology, Cambridge, lead author of a report in the Dec. 9 issue of the journal Nature. "Carbon-rich planets would be exotic in every way -- formation, interiors and atmospheres."

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